The present invention relates to a data recording method for recording various data such as voice, picture, text or the like as optically readable dot patterns on a sheet-like recording medium such as paper or the like, and to a data reproducing method for reproducing the data by optically reading dot patterns recorded on this recording medium, as well as to a data recording medium recording these dot patterns as optically readable image.
Conventionally, various data recording method for recording various data such as voice, picture, text or the like as optically readable image on a sheet-like recording medium such as paper or the like have been proposed.
This applicant has also proposed, as disclosed U.S. Pat. No. 5,896,403, U.S. Pat. No. 5,866,895 and the like, a data recording method, a data reproducing method and a data recording medium using a dot code which makes it possible to read a large volume of data manually and easily by inventing a new format utilizing fine dot patterns in the order of about 60 xcexcm to 80 xcexcm located in the two dimensions as shown in FIG. 1.
FIG. 2 shows a concrete example of the format of the dot code basically composed of a plurality of blocks located adjacently in the two dimensions.
That is, each block is composed of an area of data dots 1, markers 2 and a block address pattern 3. Here, the area of data dots 1 is an area where data divided per block of the data to be recorded exist in a predetermined two dimensional arrangement as data dots 1 which are an image of dots having reflection characteristics corresponding to the value xe2x80x9c1xe2x80x9d or xe2x80x9c0xe2x80x9d thereof, for example, black/white, same phase/inverted phase or the like. The markers 2 are used to find a reference point for reading the data dots 1 and are composed of a predetermined number of consecutively arranged black dots located at the four corners of each block. The block address pattern 3 is a pattern showing the address of the block located between the markers so that the plurality of different blocks may be identified when reading. Moreover, this block address pattern 3 includes an error detection or error correction code.
Therefore, according to this dot code, even if the whole area of this dot code is larger than the image pickup field of the data reader, that is, even if the data reader can not pick up the dot code in one shot, the whole original data can be reconstructed from the data contained in each block by detecting each address allocated to each block together with the data dots contained in each block per block and rearranging the blocks in accordance with the detected addresses. Accordingly, not only a large volume of data on pages or the like can be recorded practically, but also these data can be read easily even by means of manual operation, and therefore, the wider use of this dot code is expected in future.
However, with respect to the technology of recording or reproducing data by the dot code including fine dot patterns, it has been found by the researches thereafter that the technology still has several new points to be improved as described below.
That is, when the dot code is recorded, only the printing technology is used, and since the recorded dot code itself must be always printed with a constant quality in order to read the dot code always with stability, the resolution in recording the dot code has its limit as a matter of course, resulting in an inevitable reduction in the recording density of the dot code.
On the other hand, if the dot code can be recorded with a possible smallest area without allocating a large area on pages or the like, various beneficial effects such as an advantageous layout on pages or the like can be obtained. And therefore, there is also a desire to reduce the dot code in area and record it.
If the recording density is increased to the limit of the printing technology according to this desire, the reading resolution of the dot code reader is inevitably increased, for example, a high definition image pickup system is required, and the processing with respect to the reading becomes more expensive, resulting in an increase in cost of the reader.
Therefore, it is an important problem to be solved to be able to record and reproduce data with a higher recording density of the dot code, but with a possible lowest reading resolution of this dot code on the reader side.
Generally, a method of reading a high density recorded dot code by increasing the image pickup magnification of the optical system without increasing the reading resolution on the reader side is also conceivable, however, in this case, since the area of the dot code coming within the image pickup field becomes smaller, and since the reader and the dot pattern must be positioned more precisely, there is a new disadvantage that this method is not suitable particularly for a manual operation.
Now, this phenomenon will be described in detail with reference to FIGS. 3 to 6. For example, as shown in FIG. 3, if the width Wc of the image pickup area 4 in the image pickup portion is 8 mm, and if the width Wd of the dot code is 4 mm, the permissible snaking width W is Wcxe2x88x92Wd=4 mm. Usually, since the permissible snaking width in the order of 6 mm is required when the dot code is scanned by manual operation, countermeasures such as recording the identical data twice by arranging the dot code as shown in FIG. 4 or the like are taken. By this, the permissible snaking width W is 8 mm, however, the occupancy area of the dot code is doubled, and if the occupancy area of the original dot code is 4S, the occupancy area thereof is 8S.
Now, if the dot code is recorded with a double recording density both in length and width, the occupancy area of the dot code is xc2xc or S, and if the dot code is read by doubling the magnification of the optical system in order to obtain the same reading resolution, Wc is 4 mm, Wd is 2 mm, and therefore, the permissible snaking width W is 2 mm, as shown in FIG. 5. Accordingly, in order to secure a permissible snaking width of 6 mm, it is necessary to record data three times as shown in FIG. 6, however, since the occupancy area thereof is 3S, the substantial recording area is only xe2x85x9c compared with a case as shown in FIG. 4 in spite of a quadrupled recording density. That is, by increasing the reading resolution corresponding to the recording density, the operability by a manual scanning is impaired considerably, and if a redundant recording is made in order to prevent this, the occupancy area can not be reduced with the same efficiency even with an increased recording density.
The present invention is made in consideration of the above-described points, and has an object of providing a data recording method and a data reproducing method as well as a data recording medium being adapted to read fine dots arranged and recorded in the two dimensions so as to be readable optically with a high density particularly without increasing the reading resolution on the reader side and to reproduce data recorded as dots precisely.
According to a first aspect of the present invention, there is provided a data recording method for recording data to be recorded as an optically readable image on a recording medium by letting xe2x80x9c1xe2x80x9d or xe2x80x9c0xe2x80x9d correspond to existence or non-existence of a fine dot having predetermined reflection characteristics respectively and by arranging the dot corresponding to the data according to a predetermined format in the two dimension, the data recording method comprising the steps of:
inputting data to be recorded; and
recording dots corresponding to the inputted data optically readably so that the data may be reproduced by using a two dimensional interference from the adjacent dots.
According to a second aspect of the present invention, there is provided a data reproducing method for reproducing data by reading fine dots having predetermined reflection characteristics from a recording medium on which data to be recorded is recorded as an optically readable image by letting xe2x80x9c1xe2x80x9d or xe2x80x9c0xe2x80x9d correspond to existence or non-existence of the dot respectively and by arranging the dot corresponding to the data according to a predetermined format in the two dimension, the data reproducing method comprising the steps of:
picking up the dots from the recording medium by a manual scanning operation; and
reproducing the data from the data of the dots obtained by the pickup by using a two-dimensional interference of the dots located adjacently in the two dimension.
According to a third aspect of the present invention, there is provided a recording medium on which data to be recorded are recorded as an optically readable image by letting xe2x80x9c1xe2x80x9d or xe2x80x9c0xe2x80x9d correspond to existence or non-existence of a fine dot having predetermined reflection characteristics respectively and by arranging the dot corresponding to the data according to a predetermined format in the two dimension, the recording medium comprising:
a location area for locating the dots; and
the dots recorded within the location area, wherein the dots are recorded optically readably so that the recorded data may be reproduced by using a two-dimensional interference from the adjacent dots.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.